Mechanical vibrating screen



2 SHEETS-SHEET 1 Filed March 4. 1949 INVENTOR. LOUIS W JOHNSON BY ATTORNEY Dec. 18, 1951 L. W. JOHNSON 2,579,002

MECHANICAL VIBRATING SCREEN Filed March 4. 1949 2 SHEETS-SHEET 2 INVENTOR. LOUIS .W. JOHNSON ATTORNEY Patented Dec. 18, 1951 UNITED STATES PATENT OFFICE MECHANICAL VIBRATING SCREEN Louis W. Johnson, Eugene, Oreg.

Application March 4, 1949, Serial No. 79,640

2 Claims. (01. 209-415) This invention relates to mechanical vibrating screens and is particularly adapted for the screening of gravel, coal or any materials that require separation.

The primary object of my invention is to eliminate teeter-tottering, bouncing, galloping or any distorting motion relative to the screen. This object is accomplished by a smooth eccentric movement being imparted to the screen, the said screen being balanced by torsion spring units carrying out a uniform separation of materials.

With my new and improved torsion spring control of the screen working in combination with an eccentric movement of the same, a uniform separation is maintained through surge loads, varying speeds and so forth.

A still further object of my invention is the providing of means of adjusting the pitch of the screen without altering the position of the base frame.

These and other incidental objects will be apparent in the drawings, specification and claims.

Referring to the drawings:

Figure 1 is a side perspective view of my new and improved mechanical vibrating screen.

Figure 2 is a sectional view, taken on line 22 of Figure 1, illustrating the method of mounting the screen to the base frame and the general principle and construction of the screen.

Figure 3 is an enlarged sectional detail view taken through one of the bearing mountings, and the eccentric movement, taken on line 2-2 of Figure 1.

Figure 4 is an end sectional view, taken on line 4-4 of Figure 3, illustrating the eccentric principle of vibrating the screen.

Figure 5 is an enlarged detail fragmentary view illustrating the torsion spring unit.

Figure 6 is a fragmentary detail view taken on line 6--6 of Figure 5 illustrating the torsion spring unit assembly. a

Figure '7 is a fragmentary detail plan view, taken on line 1-! of Figure 6, illustrating the torsion spring assembly.

Figure 8 is an enlarged detail sectional view taken on line 8-8 of Figure 5, illustrating the method of mounting the torsion connecting rod to the screen.

Figure9 is an enlarged sectional detail, taken on line 9-9 of Figure 8 further illustrating this connection.

Figure 10 is a perspective view of one of the cranks for connecting the torsion connection-rods to the torsion rod.

Figure 11 is a perspective view of one of the rubber mountings used within the connecting rods which are connected to the screen and the torsion cranks.

Referring more specifically to the drawings:

My new and improved mechanical vibrating screen consists of a base frame 1. consists of side beams 2 and 3 connected together This frame at their one end by the cross member 4 and by" the cross member 5 at their opposite ends. The cross member 5 is mounted upon legs ii and l raising the same to a higher elevation, the object of which will be apparent later on.

The screen is indicated at B and consists of side plates 9 and I5. These side plates are connected together by a series of cross members I! and I2, spaced apart from one end of the screen to th other. Running longitudinal of the screen and secured to these cross members are beams l3. The beams l3 are raised slightly higher than the cross members II and I2, the object of which is to support the wire screen l4, as best illustrated in Figure 2, the wire screen [4 being crowned longitudinal of the length of the screen assembly.

The edges 15 of the screens l4 rest on the outer ends of the members II and I2 and are held down thereagainst by the angle bars i6 running longitudinal of the screen assembly. These bars are held in place by the bolts I! that pass through the side plates 9 and Ill and are held by the nuts It. By the use of the angle bars l6 and the holding bolts ll the wire sccreen I4 is held in place securely and is easily removed, exchanged or replaced. r

The screen assembly 8 is supported by the shaft I9, which is journalled in pillow blocks 28 mounted to the base frame I in the usual manner. The pillow blocks 20 contain bearings 2|. which have suitable dust rings 22 associated therewith for preventing grit from getting into the bearings. A tubular member 23 is bolted to the side plates 9 and I8 oi the screen unit at 24, the shaft l9 running through this tubular memher is protected from dust and dirt, the said member 23 further adding rigidity to the screen unit. Mounted in each end of the tubularmeinber 23 are bearings 25. These bearings also have dust protecting rings 25 associated therewith.

Referring to Figures 3 and 4, it will be noted that the shaft is is turned down to an eccentric portion 21. This eccentric portion is journalled within the bearing 25. The extension ISA of the shaft is journalled inthe bearing 2|, the said shaft coming back to the center line of the shaft is as indicated best in Figure 3. As the shaft is revolved the eccentric portion 2! imparts an eccentric movement to the screen 8. The pitch of the screen relative to the base frame is maintained at a predetermined angle by the torsion rods 23 and 29, referring to Figure 1. These torsion rods are fixedly mounted within the clamping blocks 30 and'3l, which in turn are fixedly rods or extensible links 36 are provided and consist of bars 31 and 38, the bars 38 being connected to the wrist pins or lugs 39 in the following manner. The wrist pin 39 has a collar 40 and a threaded portion extension 4|, which passes through the side plates 3 and Ill, best illustrated in Figure 8. The wrist pin is locked to the plate by the locking nut 42, referring to Figure 11.

A rubber bearing 43 is pressed into the enlarged end 44 of the connecting rods 31 and 38 and over the wrist pin 39. The rubber bearing 43 consists of an inner metal sleeve 45 having a rubber cover 46 securely fixed therearound. When this bearing unit is pressed into the ends 44 of the connecting rod this rubber cover 46 is prevented from rotating within the the enlarged end 44 by frictional engagement while the inner sleeve 45 is prevented from rotating on the wrist pin 38 by frictional engagement or other means. When the connecting rods are oscillated about the wrist pins the resilient material 46 will flex confining all movement within the fiber of the rubber, but will maintain a firm but resilient connection between the screen and the torsion rods.

The connecting bars 31 also have the torsion bearing units 43 associated therewith, which are adapted to fit over the crank pin 41 of the cranks 35. This provides a bearing between the cranks 35 and the side plates 8 and l of the screen unit 8 that will prevent any looseness or play and always tending to return to a predetermined fixed position relative to the entire torsion unit. Rub ber bearing units 43 are also installed within the pillow blocks 48, which are located adjacent the crank 35 and fixedly mounted to the cross members 4 and 5,. The rubber bearing permits partial rotation of the rods 28 and 29 under the torsion movement of the said rods.

I will now describe the operation of my new and improved mechanical vibrating screen. The extension ISA .of the shaft is driven by a power unit not here shown at a relatively high rate of speed. The eccentric portion 21 will work the screen unit 8 in an eccentric movement. As this movement takes place the connecting rods 35, the cranks 35 and the torsion rods 28 and 28 resist this eccentric movement. The torsion rods 28 and 29 are held from rotation by the stationary clamping blocks 3|. It will be noted that when the screen 8 is being raised, the connecting rods 36 and 36A are resisting in opposite directions, but each assisting each other in this resistance so that any excessive load on either end of the screen will be supported by the combined effort of the torsion units on both ends of the screen.

,The connecting rods 38 are made up of separate rods 3! and 38 secured together by the bolts 49 providing means of adjusting thelength of the connecting rods for changing the pitch of the screen within the base frame. A counterbalancing wheel 50 is keyed to the extension |9A of the shaft l9 and has an adjustable counterweight for offsetting the throw of the screen due to the eccentric action. This counterweight may be adjusted to balance the screen when lighter or heavier screens are installed within the screen unit insuring a balanced operating machine.

-Due to the particular mounting of my screen unit within the base frame 4, having the uprights 6 and 1 for supporting the cross member 5 a minimum of head room is required in the operation of this screen. The design of the base ,frame is essential to the satisfactory operation of the torsion assembly because it permits all the connecting links to always be of equal length at any degree of angular adjustment of the screen unit in relation to the base frame 4. Although certain specific embodiments of the invention have been shown and described, it is obvious that many modifications thereof are possible. The invention, therefore, is not to be restricted except in so far as is necessitated by the prior art and by the spirit of the appended claims.

What I claim is:

1. A vibrating screen assembly comprising an open supporting frame including longitudinal side beams, a cross member at one end of the side beams and a second cross member at the other end and disposed in a plane above the plane of the side beams and first cross member, a screen frame positioned within the frame for gyrating movement between the side beams and including opposed side panels, supporting torsion rods fixedly mounted against rotation at the center of the cross members and extending to the ends of the cross members for the full width of the frame, arms laterally projecting inwardly from the torsion rods and keyed to the extended ends of the torsion rods, sectional connecting links pivotally aflixed at one of their ends to the arms, the links depending from the second cross member and extending upwardly from the first, and means afiixingthe oposing ends of the links to the side panels and including sleeves formed on the said ends of the links, lugs projecting from the panel sides and received in said sleeves and resilient bushings tightly interposed between the sleeves and lugs to prevent relative movement thereof, the bushings flexing upon pivotal movement of the links about the arms as the screen frame is vibrated.

2. A vibrating screen assembly comprising an open rectangular supporting frame having one end raised above the other, a screen frame having opposed sides, stabilized supporting means mounting the screen frame within the supporting frame and including fixed supporting rods mounted against rotation at the center ofv each of the ends of the supporting frame and extend ing for the full width of the ends of the supporting frame, arms laterally projecting inwardly of the frame from the rods and keyed to the extended ends of the rods, sets of extensible links pivotally secured to the arms at one of their ends, one set of links depending from the rod on the raised end of the frame and the other set extending upwardly from the other end of the supporting frame, lugs projecting from the sides of the screen frame, sleeves formed on the opposing ends of the links and mounted on the lugsand resilient bushings tightly interposed between the lugs and sleeves to prevent relative movement thereof, the bushings flexing as the links oscillate about the arms, and means for vibrating the screen frame.

LOUIS W. JOHNSON.

REFERENCES CITED The following references areof record in the file of this patent:

UNITED STATES PATENTS 

